Applicator device with self-tapping piston

ABSTRACT

The invention relates to an applicator device for applying, e.g., a viscous fluid or a gel, with the use of a self-tapping piston. The device comprises a piston provided with a blade, the cutting edge of which is inclined in relation to the longitudinal axis of a rod passing through the piston. The cutting edge of the blade projects into a space defined in the piston through which the rod passes and bites into the relatively soft, smooth outer surface of the rod as the rod is rotated. The blade cuts into the surface of the rod during such rotation in a substantial spiral direction, causing the piston to move along the rod.

FIELD OF THE INVENTION

The present invention relates in a general manner to a device fordriving a part in translatory motion by the rotation of a rod or thelike extending through the said part.

It relates more particularly to an apparatus for applying a more or lessviscous fluid such for example as nail varnish fitted with this device.

BACKGROUND OF THE INVENTION

One knows that the hydraulic jacks consist in general of a rod whichpushes a piston in a cylinder. But the bulkiness exhibited by such jacksis about twice the length of the rod thereby constituting aninconvenience when one must use them in an apparatus having necessarilyto exhibit a very small bulkiness.

On the other hand one has already proposed systems in which anexternally threaded rod extends through a piston held immovable againstrotation so that the rotation of the rod permits the translatory motionof the piston along the said rod.

But such a system is not free of drawbacks, in particular in connectionwith the fluid-tightness between rod and piston, which fluid-tightnessoften is imperfect let apart the possible fouling of the system.

SUMMARY OF THE INVENTION

Therefore the present invention has as its object to remedy theabove-identified drawbacks by proposing a structure driving deviceadapted to impart all the required fluid-tightness qualities to betweenrod and piston.

For that purpose and in a general manner the present invention has asits subject a device for driving a part in translatory motion by therotation of a rod or the like extending through the said part which isheld immovable against rotation, characterized in that the said part isprovided with at least one blade the cutting edge of which is inclinedwith respect to the longitudinal axis of the rod and projects sidewisethrough the aperture of the part through which extends the rod in orderto be caused to bite in the external smooth periphery of this rod so asto cut helically therein during its rotation and thus cause thetranslatory motion of the part along the rod during this rotation.

One therefore already understands that the blade constitutes a simplemeans to permit the translatory motion of the part under the effect ofthe rotation of the rod.

According to a first embodiment the blade is mounted in the part so thatits plane is substantially perpendicular to the plane tangent to theexternal side surface of the rod, the said plane being parallel to thecutting edge of the blade.

According to another embodiment the blade is mounted in the part so thatits plane is inclined with respect to the plane tangent to the externallateral surface of the rod, the said plane being parallel to the cuttingedge of the blade.

One should specify here that in this case the plane of the bladepreferably is inclined with respect to the aforesaid tangent planetowards the direction of advance of the aforesaid part.

According to a particular embodiment the cutting edge of the blade maybe in the shape of a right-angled dihedron and may be constituted by onearris of an edge of a parallelepipedic plate.

According to still another characteristic of the invention, theinclination of the cutting edge of the blade with respect to the axis ofthe rod is such that the axial component of the force exerted upon theblade by the effect of the rotation of the rod is clearly greater thanthe tangential component of this force.

In another embodiment of the invention the blade consists of severalblades mounted and arranged in the part so that their cutting edges aredirected along a regular cylindrical helix or form one single blade thecutting edge of which follows a regular cylindrical helical line.

The aforesaid blades may be formed of the two mutually confronting legsof a substantially U-shaped deformable member the legs of which areinsertable into two apertures, respectively, which are formed obliquelyin the aforesaid part and which are axially offset and extend on eitherside of the axis of the said part.

According to another embodiment the aforesaid blades are cut out in awasher made fast to the aforesaid part.

The washer comprises a folded-back portion which permits it to be hookedonto an element which is attached to the aforesaid part.

In the case of one single blade with a cutting edge of helical shape,this blade may be formed from a plunged boss formed in a washer or thelike.

According to still another characteristic of the device according tothis invention, the aforesaid part is provided with at least one sealingjoint located forward of the aforesaid blade or blades to alwaysco-operate with the external smooth periphery of the rod so that thefluid-tightness between rod and part is maximized.

According to a preferred embodiment the aforesaid part is constituted bya piston which slides in a fluid-tight manner in a hollow body forming acontainer whereas the rod is actuated for rotation on one side of thepiston by a suitable means such as a rotary knob, a push-button or thelike, the other side of the piston defining a product tank with thehollow body.

The aforesaid rod may be a hollow rod one end of which opens into thetank.

The device of this invention is further characterized by at leastanother sealing joint between the periphery of the piston and the wallof the hollow body.

The device of the invention is further characterized by an applicatormeans such as a paint brush, a brush or a foam, felt or velvet tipmounted on the other end of the hollow rod.

One should further specify here that the other aforesaid end of thehollow rod forms a head projecting from the hollow body and sealedthereto with another sealing joint.

The aforesaid piston-like part could be provided with a cutting elementsuch as a blade which cuts longitudinally into the internal periphery ofthe hollow body to hold against rotation the piston during its advancingmotion within the said hollow body.

The device forming the subject of this invention may advantageously beapplied to the provision of an apparatus for applying a more or lessviscous fluid such for example as a cream or nail varnish.

BRIEF DESCRIPTION OF THE DRAWINGS

But further advantages and characteristics of the invention will appearbetter in the detailed description which follows and refers to theattached drawings given by way of example only and in which:

FIG. 1 is an elevational view in axial section of an applicatorapparatus fitted with the device according to this invention;

FIG. 2 is a partial and enlarged perspective view illustrating theposition of the blade with respect to the rod;

FIG. 3 is a view similar to FIG. 2 but illustrating another type ofblade and another relative position of this blade with respect to therod;

FIG. 4 is a perspective view of another embodiment with several bladesarranged along a regular cylindrical helix, the rod being not shownhere;

FIG. 5 is a partial view in axial section of the device of the inventioncomprising the blades of FIG. 4;

FIG. 6 is a perspective view of the device of the invention adapted tobe fitted with another embodiment of blade;

FIG. 7 is a view in section along the line VII--VII of FIG. 6 andshowing the blades in operative position mounted on the piston;

FIG. 8 is a side view of a washer in which are cut out and shaped theblades arranged according to the invention;

FIG. 9 is a front view of this washer according to the arrow IX--IX ofthe figure;

FIG. 10 is a perspective view of a piston-shaped part with which isassociated a washer similar to that shown on FIGS. 8 and 9;

FIG. 11 is a perspective view of another embodiment of washer;

FIG. 12 is a partial view in axial section of the device of theinvention fitted with the washer according to FIG. 11; and

FIG. 13 is a view in axial section of an applicator apparatus fittedwith a washer according to FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the exemplary embodiment shown in FIG. 1, the deviceaccording to this invention fits an applicator apparatus 1 essentiallycomprising a hollow body 2 forming a container for any more or lessviscous liquid 3 such as a nail varnish for example.

In the body 2 is axially slidably mounted a piston 4 provided with acentral aperture 5 through which extends a rod 6 which is hollow andexternally smooth.

This hollow rod 6 opens at one end 6a into a fluid tank R defined by thehollow body 2 and one side 4a of the piston 4 which comprises on itsperiphery one or more sealing joints such as 7. These joints which aredescribed below, hold the piston 4 immovable against rotation under theeffect of the rotation of the operating rod 6 without however preventingthe translatory motion of the piston 4 in the body 2.

The rod 6 on the side 4b of the piston 4 is rotatably driven by a knob 8co-operating with the external periphery of the said rod by any suitablemeans as shown at 9. The knob 8 may for example rotate and comprises athread which meshes with a pinion made fast to the rod 6 or the knob 8may further be a push-button provided with a toothed rack andcooperating with a ratchet wheel made fast to the rod 6 so that animpulse upon the knob 8 causes a short rotation of the rod 6 andtherefore a translatory motion of the piston 4 which compresses theliquid 3 within the tank R. Thus as shown by arrows on FIG. 1, the fluidwill pass through the rod 6 to flow out through the other end 9 of thisrod comprising an applicator brush 10. The end 9 forms in a way a headwhich projects in a fluid-tight fashion from the hollow body 2 owing toa seal designated at 11 on FIG. 1.

All the arrangements described hereinabove are known per se and do notrequire detailed explanations.

According to the invention and as one sees it on FIG. 1 in the piston 4also referred to as a "part" in this description is mounted at least oneblade 12 the cutting edge 13 of which is inclined with respect to thelongitudinal axis X-X' of the rod 6.

More specifically the cutting edge 13 of the blade 12 projects into theaperture 5 of the part or piston 4 through which extends the rod 6 inorder to cause cutting edge 13 to bite into the external smooth andrelatively soft periphery of this rod so as to cut helically therein asone sees it at 14 during its rotation and to thus cause the translatorymotion of the part 4 along the rod 6 during this rotation. In otherwords, rotating the externally smooth rod 6 by the knob 8 would generatea threading on this rod which causes the part 4 to move forward in thedirection shown by the arrow F.

The angle α (FIGS. 2 and 3) of inclination of the self-tapping cuttingedge 13 of the blade 12 with respect to a direction orthogonal to theaxis X-X' of the rod 6 should of course be an acute angle so as topermit the formation of the helical groove 14 permitting thedisplacement of the part or piston 4 which as one will recall is heldimmovable against rotation for example owing to the sealing joints 7.

This angle α will have such a value that the axial component of theforce exerted upon the blade 12 by the effect of the rotation of the rod6 is greater than the tangential component of this force. For examplethe axial component which tends to cause the part 4 to move along therod 6 may be about 5 to 10 times higher than the tangential componentwhich tends to cause the part 4 to turn about the rod 6. Thischaracteristic is particularly important in the case where the part 4comprises a piston as shown in FIG. 1 and where it is prevented fromrotating by the friction forces of the sealing joints 7 against theinternal wall of the hollow body 2.

The blade 12 as it appears clearly in FIG. 2 comprises a cutting edge 13in the shape of a dihedron which is here provided by a simple bevelling,it being understood that a sharpening according to any angle whatsoeverof the blade may be provided without departing from the scope of theinvention. Moreover one sees in FIG. 2 that the plane of the blade 12mounted in the part 4 is substantially perpendicular to the externalsmooth surface of the hollow rod 6, i.e. more specifically to a planetangent to the external side surface of the rod 6, the said tangentplane being parallel to the cutting edge 13 of the blade 12.

In the embodiment illustrated by FIG. 3, the cutting edge 13 of theblade 12 is in the shape of a right-angled dihedron constituted by onearris of an edge 13a of a parallelepipedic plate. Therefore the blade 12is here mounted in the part 4 so that its plane is inclined as shown bythe angle β upon the external surface of the hollow rod 6. Morespecifically the plane of the blade 12 is inclined with respect to aplane tangent to the external lateral surface of the rod 6, the saidtangent plane being parallel to the cutting edge 13 of the blade.

In the embodiment of FIG. 4, the blade comprises a plurality of blades15, three according to the example shown mounted in the part or piston 4so that their cutting edges 15a all follow a regular cylindrical helixhaving the same pitch. Preferably the helices generated by the bladesare coincident with one single regular cylindrical helix S therebyreducing the force to be exerted for causing the rod 6 to turn.

These blades 15, as also shown in FIG. 5 may be mounted in the part 4 inany suitable manner not shown. The same is true for case of the blade 12illustrated in FIGS. 2 and 3.

One clearly sees in FIG. 5 the helical groove 14 formed on the outsideof the rod 6 during the rotation of the latter as shown by the arrow Fwhich permits the displacement of the piston 4 towards the right of FIG.5.

In the alternative embodiment illustrated by FIGS. 6 and 7, the bladecomprises two blades 16 constituted by the two mutually confronting legsof a U-shaped member 17. The blades or legs 16 of the U 17 areinsertable into two apertures 18, respectively, which are formed in thepart 4 and which are actually offset as shown in FIG. 6. Thus theapertures 18 pressure blades 16 onto the surface of rod 6 on either sideof its axis x-x' while imparting to these blades a proper inclination onthe said axis. As clearly shown in FIG. 7, the mutually confrontingedges 16a form the cutting edges of the legs or blades 6 which will cutinto the external surface of the hollow rod 6.

It is perfectly possible to provide other embodiments for the bladeswithout departing from the scope of the invention. Thus as shown inFIGS. 8 and 9 the blades may comprise two mutually confronting blades 41which are cut out in a washer 40 which may be made fast to the part orpiston 4 by any suitable means.

For example as shown in FIG. 10 the washer 40 may assume a substantiallyrectangular shape and be bent over itself so that one folded-backportion 43 of this washer may be hooked onto an element 44 made fast tothe part or piston 4. One sees at 44a on FIG. 10 a recess formed in theelement 44 and into which is inserted the folded-back portion 43 of thewasher 40. It should be noted that the element 4 could also be mouldedover the washer 40 the blades 41 of which comprise cutting edges 41awhich become engaged with the rod 6 to generate the helical groove 14therein.

FIGS. 11 and 12 illustrate another embodiment of the washer 45 having aplunged boss 47 defining a blade 46 with a cutting edge 46a of helicalshape. This washer 45 as shown in FIG. 12 is mounted for example byhaving the part or piston 4 being moulded over the said washer.

Reverting to FIG. 1 one sees that the piston 4 is fitted with a packingseal 19 which ensures fluid-tightness between the said piston and thehollow rod 6. As explained at the beginning of this description, thefluid-tightness at this level will always be outstanding owing to thefact that the packing seal 19 co-operates with the smooth periphery ofthe rod 6 since the helical groove 14 is formed on this rod only behindthe packing seal.

FIGS. 5 and 12 illustrate another embodiment of the sealing joint whichis comprised of a single sealing joint 20 capable of performing byitself the function of the sealing joints 7 and 19 ensuring thefluid-tightness between the hollow body 2 and the piston 4 and thefluid-tightness between the piston 4 and the hollow body 6,respectively.

Referring again to FIG. 5 one sees that the piston-like part 4 may beprovided with a cutting element 30 such as a blade which cutslongitudinally into the internal periphery of the hollow body 2 toadvantageously hold the piston 4 immovable against rotation during itsadvancing motion within the hollow body.

Such a cutting element may also be provided on a washer with cut-outblades shown at 42 on FIG. 9.

The application device of FIG. 1 is operated in accordance with thedescription provided herein.

The knob 8 could impart to the hollow rod 6 a rotation comprised forexample between 1/4° and 1/16° of revolution. During this rotation theblade or blades made fast to the piston 4 will cut into the rod 6according to an angle representing the slope of the helical groove 14.

The tangential component of the force exerted upon the blade by theeffect of the rotation of the rod 6 is compensated for by the rubbing ofthe sealing joint or joints 7 between the piston 4 and the hollow body 2so that as noted above the sealing joint or joints 7 hold the part 4immovable against rotation. The axial component is great enough (about 5to 10 times higher than the tangential component as previously explainedto overcome the axial friction forces of the sealing joints of thepiston between the piston 4 and the hollow body 2 and between the piston4 and the rod 6), so as to cause the said piston to move forward in afluid-tight manner and without any rotation about its axis in the hollowbody 2.

Referring to FIG. 13, there is shown an embodiment of the applicatordevice according to the invention provided with a washer 45 visible inFIG. 11, it being well understood that another type of washer aspreviously described could be used.

In FIG. 13 the hollow body 2 forming a tank R is open at one of its endsand shaped so as to be capable of receiving a cap 39 co-operating in afluid-tight manner with the body 2 for example by means of one orseveral annular bosses 39a.

At the other end of the body 2 and outside thereof a rotary knob 38 isprovided which permits rod 6, which in this embodiment is solid, to berotated.

On rod 6 and in the tank R is retained a solid gel constituting forexample a deodorant cosmetic "stick" which will be usable after removalof the cover 39 and actuation of the knob 38.

It should be noted here that the perfect fluid-tightness between thepiston 4 and the solid rod 6 as this has been previously explained willadvantageously avoid, over time, any desiccation of the product 33 aswell as any substantial decrease of its fragrance.

The invention is of course not limited to the embodiments described andillustrated which have been given by way of example only. Thus the angleof sharpening the blades, their number and their flat or curved shapemay be of any character without departing from the scope of the presentinvention. Likewise instead of being hollow the rod for operating thepiston could be solid in which case an aperture would be provided in thetank to permit the delivery of fluid. The means for operating this rodmay also be any means whatsoever and others than those described andshown. In addition the device according to this invention may find anapplication in systems or apparatus others than a fluid applicatorapparatus.

This means that the invention comprises all the technical equivalents ofthe means described as well as their combinations if the latter arecarried out according to its gist.

We claim:
 1. A device for driving in translatory motion a part by therotation of a rod extending through the part which is held immovableagainst rotation, wherein said part is provided with at least one blade,the cutting edge of which is inclined with respect to the longitudinalaxis (x-x') of the rod and which is caused to bite into the externalsmooth periphery of said rod so as to cut it helically during itsrotation and thus cause the translatory motion of the part along the rodduring this rotation.
 2. The device according to claim 1, wherein the atleast one blade is mounted in the part in such a manner that its planeis substantially perpendicular to a plane tangent to the external sidesurface of the rod wherein the tangent plane is parallel to the cuttingedge of the blade.
 3. The device according to claim 1, wherein the atleast one blade is mounted in the part in a manner such that its planeis inclined with respect to a plane tangent to the external lateralsurface of the rod, said tangent plane being parallel to the cuttingedge of the blade.
 4. The device according to claim 3, wherein the planeof the at least one blade is inclined with respect to the tangent planetowards the direction of advancing motion of the part.
 5. The deviceaccording to claim 1, wherein the angle (α) of inclination of thecutting edge of said at least one blade with respect to a directionorthogonal to the axis of the rod is such that the axial component of aforce exerted upon the at least one blade by the effect of the rotationof the rod is greater than the tangential component of this force. 6.The device according to claim 1, wherein said at least one bladecomprises a plurality of blades mounted and arranged in the part suchthat their cutting edges are directed along a regular cylindrical helix.7. The device according to claim 6, wherein said blades are formed oftwo mutually confronting legs of a substantially U-shaped deformablemember the legs of which are inserted into two apertures, respectively,which are formed obliquely in the part and which are axially offset andextend on either side of the axis (x-x') of the rod.
 8. The deviceaccording to claim 6, which further comprises a washer made fast to thepart, wherein said blades are cut out from said washer.
 9. The deviceaccording to claim 8 wherein the washer comprises a folded-back portionwhich permits it to be hooked onto an element made fast to the part. 10.The device according to claim 6, wherein the blade with a cutting edgehaving a helical shape comprises a plunged boss formed on a washer. 11.The device according to claim 7 wherein the cutting edge of the at leastone blade is in the shape of a right-angle dihedron constituted by onearris of an edge of a parallelepipidic plate.
 12. The device accordingto claim 1, wherein the part is provided with at least one sealing jointlocated forward of the at least one blade such that said at least onesealing joint cooperates with the external smooth surface of the rod.13. The device according to claim 1 wherein the part comprises a pistonwhich slides in a fluid-tight manner in a hollow body forming acontainer, wherein the rod is actuated for rotation on one side of thepiston by means for rotating said rod and wherein the other side of thepiston defines a product tank within the hollow body.
 14. The deviceaccording to claim 13, further comprising at least one additionalsealing joint located between the periphery of the piston and a wall ofthe hollow body.
 15. The device according to claim 1, wherein the partis provided with a cutting element which cuts longitudinally into theinternal periphery of the hollow body to prevent rotation of the pistonduring its forward motion within the hollow body.
 16. The deviceaccording to claim 1, wherein the part is a hollow rod, one end of whichopens into the tank.
 17. The device according to claim 16, which furthercomprises means for applying a fluid mounted onto the other end of thehollow rod.
 18. The device according to claim 16 wherein said other endof the hollow rod forms a head projecting from the hollow body, saidhead being rendered fluid-tight with said hollow body by an additionalsealing joint.
 19. The device according to claim 1, which comprises asingle blade, having a cutting edge which follows a regular, cylindricalhelical line.
 20. The device according to claim 1, wherein said deviceis for applying a viscous fluid.
 21. The device according to claim 1,wherein said device is for applying a substantially solid gel.